build(deps): bump ubuntu in /tools/ubuntu-cross

Bumps ubuntu from `186072b` to `84e77de`.

---
updated-dependencies:
- dependency-name: ubuntu
  dependency-version: noble
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

tools/ubuntu-cross/Dockerfile

@@ -1,5 +1,5 @@
 FROM --platform=${BUILDPLATFORM} tonistiigi/xx:master@sha256:7e8c9d88e47741bb0d35981494920eee2857cd75a40193567fe6c1a16adf785d AS xx
-FROM --platform=${BUILDPLATFORM} ubuntu:noble@sha256:186072bba1b2f436cbb91ef2567abca677337cfc786c86e107d25b7072feef0c AS build
+FROM --platform=${BUILDPLATFORM} ubuntu:noble@sha256:84e77dee7d1bc93fb029a45e3c6cb9d8aa4831ccfcc7103d36e876938d28895b AS build
 COPY --from=xx / /
 
 RUN <<EOF